Here is a good explanation of CANBUS HID Kits.
To truly understand the functions of a CAN BUS ballast for use in HID lighting, you must first understand the role of the CAN BUS network in an automotive electrical system and how it operates. CAN stands for “Controller Area Network” and BUS meaning pathway or data transfer channel, is a communication standard created by Bosch for automotive, industrial, and medical devices. CAN BUS networks are utilized where devices can all use the same pathway/channel to speak to one central CAN BUS controller. CAN is one of the five supported standards of vehicle diagnostics in today’s OBD-II (On Board Diagnostics) system, which also is the system responsible for displaying the dreaded “Service Engine Soon” light on your dash.
In today’s vehicles, there are several Electronic Control Units used to control and monitor the many subsystems. Your headlights, if monitored or controlled by a CAN BUS device, engine, A/C system, airbags, door locks, and Tire Pressure Monitoring System are all either independently operated with an ECU, or work together through a CAN BUS system. When a vehicle comes with a CAN BUS lighting system, what it does is monitor that a particular bulb is working. This can cause a problem when replacing a traditional light bulb with an LED or an HID system because they will not “read” the same to the CAN BUS controller and it will assume the light bulb is burnt out – this will either result in an error message being displayed to the driver, a flashing problem or no power being delivered at all.
Why do my HID headlights flash?
One of the ways that a CAN BUS system can affect the operation of an aftermarket HID conversion kit is this: First, the CAN BUS system will detect that whatever is plugged into the original wiring is probably a bad light bulb, it will start pulsating the electricity again and again in order to try to get the light bulb to start up. If it was indeed a broken factory light bulb, this would have no consequence because the electricity wouldn’t go anywhere, due to the broken filament. With an HID system, this rapid-fire electricity will cause the ballast to turn on and off like a strobe.
The way to solve this problem is to either install a CAN BUS HID Ballast or a warning canceller module. Both of these products will trick the computer in the car into thinking that a good working light bulb is plugged in, and not send pulsating electricity down the line!
